Louver sign transmission system

ABSTRACT

A transmission system for louver type signs wherein the signs consist of a plurality of multiple faced louvers having indicia defined thereon and the side-by-side relationship of the louvers permits pre-selected faces to define a completed image and simultaneous partial rotation of the louvers presents a new visible image, and wherein, each louver is operated by a separate &#34;T&#34; drive bevel gear transmission having an output shaft upon which a louver is mounted operatively connected to a drive shaft perpendicularly related to the output shaft. The drive shafts of adjacent transmissions are interconnected and a plurality of transmissions are simultaneously operated by a single motor drive source. The cost of the transmissions is significantly reduced by the use of a unique bearing support system for the drive and output shafts eliminating the need for separate bearings in that the material of the transmission casing constitutes the shafts&#39; bearing surfaces.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention pertains to "T" drive bevel gear transmissions for louvertype signs wherein a plurality of multifaced elongated louvers haveindicia or images appearing on the faces thereof wherein pre-determinedfaces aligned in co-planar relationship produce a complete image, andpartial simultaneous rotation of the louvers changes the appearance ofthe sign by making another louver indicia bearing face visible.

2. Description of the Related Art

Louver type signs require that a plurality of relatively long and narrowelements or louvers be mounted in side-by-side relationship wherein, asthe louvers are indexed to present different faces for observation thelongitudinal edges of adjacent louvers will be closely spaced as topermit a continuity of images appearing on a plurality of adjacentlouver faces. The louvers are usually provided with three sides orfaces, and the louvers are usually indexed at a pre-determined timecycle, such as to "show" a different louver face about every minute.Accordingly, with a three sided louver, the rate of indexing, orrotation, of a louver may be one-third of a revolution per minute.

In the past, it has been the common practice to simultaneously rotate orindex the louvers constituting a complete sign by means of a belt orchain arrangement. Each of the louvers includes a drive mechanismoperatively connected to a belt or chain system whereby a motor drivingthe belt or chain system will periodically operate to index the louversto present a new visible louver face. With a three sided louver, only a120° rotation of the louver is required during each indexing cycle.

In order to provide optimum sign appearance wherein the images ofadjacent louvers visibly blend and align with each other, it isnecessary that the louvers accurately operate together and indexaccurately. Louver drive systems using belts and chains encounter anumber of problems which adversely affects the operation and accuracy ofindexing of the louvers. Malfunctioning will occur due to stretching orslipping of the belts or chains, breakage of the belts or chains, andproblems occur maintaining the belts or chains in proper alignment intracking and driving relationship to the associated sprocket or pulley.

With present transmissions for louver type signs, the dependability andlong term maintenance-free operation desired has not been available, andlouver type signs are expensive to operate and service.

OBJECTS OF THE INVENTION

It is an object of the invention to provide a louver type signtransmission system wherein adjacent louver transmissions are of thegear driven type, and belt or chain drives between adjacent louvertransmissions is eliminated.

An additional object of the invention is to provide a transmissionsystem for louver type signs wherein each louver is provided with a geartype transmission, and adjacent transmissions are positivelyinterconnected in driving and driven relationships in order to producesimultaneous operation of a plurality of interconnected transmissions,and produce simultaneous louver indexing.

Yet another object of the invention is to provide a transmission systemfor louver type signs wherein each louver is associated with a gear typetransmission having drive and output shafts, and the transmissions areof an inexpensive, yet dependable, construction.

A further object of the invention is to provide a gear type transmissionfor louver type signs wherein the transmission includes drive and outputshafts rotatably supported within a casing having interconnectableparts, the casing material, itself, constituting the bearing for thetransmission shafts, and the casing parts being of such construction asto accurately position the shafts and maintain shaft position duringtransmission operation.

SUMMARY OF THE INVENTION

Louver type signs usually consist of a plurality of elongated louvers orelements arranged in side-by-side vertical relationship. Each of thelouvers includes a plurality of indicia bearing faces, and as the usuallouver construction uses three faces, the louvers are usually of atriangular transverse cross section. The louvers constituting a sign aresimultaneously indexed whereby the planar surface of a louver face isco-planar with an adjacent louver face and the longitudinal lateraledges of the visible faces of adjacent louvers are disposed close toeach other wherein indicia appearing on one louver is continued byindicia defined on an adjacent louver, and the adjacent relationship ofthe edges of the louver faces produce the appearance of a continuousimage. By indexing the louvers about their longitudinal axes to makeanother indicia bearing face visible, the entire image of the completesign may be rapidly changed, and louver type signs, although expensiveto install and operate, are used in indoor and outdoor advertising athigh traffic density locations wherein three separate advertisers mayappear on a single sign, or a single advertiser may sponsor threedifferent sign images of graphics and text.

In the practice of the invention, the lower end of each louver ismounted upon a support pad located at the end of a gear typetransmission output shaft. The output shaft is rotatably located withina gear transmission casing consisting of two parts interconnected bythreaded screws or bolts.

Each louver transmission includes a drive shaft rotatably supportedwithin its transmission casing and each drive shaft includes an inputportion and an output portion. A bevel gear mounted upon the drive shaftwithin the transmission casing meshes with a bevel gear mounted upon theoutput shaft wherein rotation of the drive shaft produces an equalrotation of the output shaft and associated louver. A thrust bearingmounted upon the output shaft supports the weight of the louver.

The axes of the drive shafts of the transmissions are coaxially related,and the input portion of each drive shaft is connected to the outputportion of an adjacent transmission drive shaft by a torque transmittingconnector, while the output portion of each drive shaft is connected tothe input portion of the adjacent transmission. In this manner, thedrive shafts, and output shafts, of each transmission are simultaneouslyoperated.

Rotation of the interconnected drive shafts may be produced by anelectric motor operatively connected to one of the drive shafts by achain sprocket, gearing, or other conventional drive system.Accordingly, when the transmission drive shaft connected to the motor isindexed by its motor for 120°, all of the interconnected drive shaftswill index a similar extent producing a similar indexing of the outputshafts and associated louvers.

Because the rate of rotation of the drive shafts and output shafts isslow, for instance, one-third of a revolution per minute, expensivebearing structure for the transmission drive shafts and output shafts isnot required. The transmission casing parts may be cast of an aluminummaterial, and the steel drive and output shafts directly engage thematerial of the casing parts.

In the practice of the invention, separate bearings for the drive shaftsand output shafts are not utilized, and this construction significantlyreduces the cost of the transmissions with respect to similar devicesutilizing sleeve or anti-friction bearings, and in the practice of theinvention, one of the casing parts has a semi-cylindrical recess definedin the casing parting surface which is of a diameter substantially equalto the associated drive or output shaft and this recess accuratelylocates the associated drive or output shaft with respect to thetransmission casing and associated structure.

A generally semi-cylindrical recess is also defined in the othertransmission casing part in opposed relationship to the previouslymentioned casing part, however, the second recess is of a diameterlarger than the diameter of the associated drive or output shaft, andthe circumferential extent of the second recess is less than 180°.Accordingly, a central apex is defined in the second recess midwaybetween the intersection with the associated casing part partingsurfaces. When assembling the transmission casing parts, the apex of thesecond recess will engage the associated drive or input shaft in linecontact holding the opposed portion of the drive or input shaft withinthe semi-cylindrical recess of the other casing wherein, in effect, thedrive or input shaft is engaged throughout approximately one-half of itscircumference, but is firmly maintained within the recess of the firstcasing part by the force exerted on the associated shaft by the apexengagement of the second recess with the shaft circumference. Bysupporting the transmission drive shaft and output shaft in the abovemanner, the shafts will be accurately located within the transmissioncasing by the first casing part recess, and the material of the casingparts directly serves as the bearing material for the shafts.

The transmission casing parts are economically formed of aluminum orsimilar material by injection molding, and as the drive shafts and inputshafts, and associated bevel gearing, may be economically manufactured,and the casing readily assembled, transmission casings constructed inaccord with the invention economically compare with previous louver typesign drive systems, and the elimination of separate bearings for thedrive and output shafts eliminates costly assembly and bearing costs.Louver type signs constructed in accord with the inventive concepts aremore dependable in operation than previous type louver type signtransmission systems, and the objects of the invention are achieved bythe apparatus disclosed and claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The aforementioned objects and advantages of the invention will beappreciated from the following description and accompanying drawingswherein:

FIG. 1 is a partial elevational detail view of a louver type signillustrating a plurality of interconnected transmissions,

FIG. 2 is an enlarged perspective view illustrating a pair ofinterconnected transmissions,

FIG. 3 is an elevational sectional view illustrating the chain driveapparatus for rotating the transmission drive shafts as taken alongSection 3--3 of FIG. 2,

FIG. 4 is a top plan sectional view of a louver and louver supportingpad as taken along Section 4--4 of FIG. 2,

FIG. 5 is an elevational view of the primary transmission casing halfwith the secondary casing half being removed,

FIG 6 is an enlarged elevational sectional view as taken along Section6--6 of FIG. 5, prior to the installation of the opposed casing half,and

FIG. 7 is an elevational sectional view similar to FIG. 6 illustratingthe casings interconnected and the apex of the second casing recessengaging the drive shaft.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A general partial elevational detail view of a louver type signutilizing the concepts of the invention is shown in FIG. 1. In FIG. 1,the lower portion of the louvers 10 are illustrated, and the lower endof the louvers 10 are each connected to a transmission generallyindicated at 12. The transmissions 12 are mounted upon the underside ofan elongated support plate frame 14 which constitutes the primarysupport for the transmissions and the louvers. Normally, the louvers 10will be vertically oriented and the support frame plate 14 horizontallydisposed. However, it is possible to construct a louver type signwherein the louvers are horizontally disposed.

Typically, a louver 10 is of a triangular cross sectional configurationas will be apparent from FIGS. 2 and 4, and the louver includes threeexterior faces 16, 18 and 20 of equal dimension interconnected at theiredges 22. The faces 16-20 are planar, and as well known, indicia, suchas text or graphic art, is applied to the faces 16, 18, or 20 wherebythe indicia formed on adjacent visible faces blends with the indicia onthe adjacent louver faces wherein the composite indicia on faces 16, forinstance, will simultaneously be visible on all of the louvers whereinthe composite indicia defines a single billboard, sign or image.Different indicia than that appearing on faces 16 will be applied to thefaces 18 wherein coplanar alignment of the faces 18 will result in adifferent sign upon a 120° rotation of the louvers 10, and likewise, afurther 120° rotation of the louvers will make the faces 20 visiblepermitting a third image to be visible upon partial rotation of thelouvers about their longitudinal axes.

Each of the louvers 10 is mounted upon a triangular louver pad 24 havinga planar support surface 26 formed thereon. A plurality of bosses 28,FIG. 4, extend from the support surface 26 and are of such dimension andlocation as to be firmly received within the interior corners of thelouver as appreciated from FIG. 4. The louver lower edge 30 rests uponthe louver pad support surface 26, and in this manner each louver 10 issupported by its associated pad 24 and rotatable about its longitudinalaxis upon rotation of the associated pad 24.

Each louver pad 24 is mounted upon a separate transmission 12, and eachtransmission 12 includes a casing 32, FIG. 2. Each transmission casing32 is identical, and includes a main or primary casing part 34 whichconstitutes a half of the casing. The casing part 34 is preferablyinjection molded of an easily moldable metal such as of an aluminumcomposition, and the part 34 includes a flat parting surface 36, FIG. 5,which is in opposed relationship to the parting surface of the secondarycasing part as later described.

The casing part 34 includes a pair of semi-cylindrical drive shaftreceiving recesses 38 and 40, FIG. 5, which have coaxial axes. Also, thecasing part includes a semi-cylindrical recess 42 having an axisperpendicular to the axes of recesses 38 and 40 for receiving thetransmission output shaft. The recesses 38, 40 and 42 are of a truesemi-cylindrical configuration wherein the plane of the casing partingsurface 36 constitutes a diameter of these semi-cylindrical recesses.

The recesses 38 and 40 intersect an enlarged chamber 44 defined in thecasing part 34, and a smaller thrust bearing chamber 46 is also definedin the casing part as intersected by the recess 42.

The transmission drive shaft 48 is received within the recesses 38 and40 as will be appreciated from FIG. 5, and the transmission output shaft50 is received within the semi-cylindrical recess 42. The output shafts50 extend through the frame plate 14. The louver pad 24 is mounted uponthe upper end of the drive shaft 50 as will be appreciated from FIG. 2.

A bevel gear 52 is mounted upon the drive shaft 48 for rotationtherewith as located within the chamber 44, FIG. 5, and a similar bevelgear 54 located upon the inner end of the output shaft 50 is locatedwithin chamber 44 in meshing relationship with gear 52. The gears 52 and54 are identical in diameter and tooth size wherein one rotation ofdrive shaft 48 will result in a single rotation of output shaft 50. Athrust bearing 56 is mounted upon the output shaft 50 within the chamber46, and the thrust bearing 56 supports axial forces imposed upon theoutput shaft 50 due to the weight of the louvers 10.

A plurality of annular bosses 58 extend from the parting surface 36, andinternally, each of the bosses 58 is provided with a threaded hole 60for receiving the screw fasteners which interconnect the casing parts,as later described.

At its upper end, FIG. 5, the casing part 34 is provided with a topsurface 62, and a pair of threaded mounting screw receiving holes 64intersect the top surface 62 whereby the transmissions 12 may beattached to the underside of the support frame 14 by bolts, not shown.

The drive shaft 48 consists of a single component having a reduceddiameter portion within the chamber 44 as will be appreciated from FIG.5, however, the portions of the drive shaft 48 rotatably located withinthe recesses 38 and 40 are of an equal diameter. The portion of thedrive shaft 48 located within recess 38 constitutes an input portion 66of the drive shaft while the drive shaft portion 68 located within therecess 40 constitutes an output portion 68 of the drive shaft. Aconnector 70 is mounted upon the input portion 66 of the drive shaft andincludes a diametrical slot 72 as will be appreciated from FIGS. 2 and5. A similar connector 70 is also mounted upon the output portion 68 ofthe drive shaft, in the drawings the connectors 70 mounted on a commonshaft 48 are rotationally disposed at 90° to each other. The connectors70 of adjacent transmissions 12 are interconnected in a torquetransferring manner by a cross shaped key 74 which includesperpendiculary related fingers having radial surfaces which are closelyreceived within the slots 72 of the adjacent connectors 70 as will beappreciated from FIG. 2 to interconnect adjacent drive shafts 48. Theconnectors 70 and key 74 are of a conventionally available constructionpermitting the drive shafts 48 of adjacent transmissions to beinterconnected in driven and driving relationship to adjacenttransmissions and drive shafts, and the connectors 70 and key 74 willpermit slight drive shaft misalignment while interconnecting the driveshafts of adjacent transmissions in a torque transmitting relationship.Accordingly, it will be appreciated that due to the driving and driveninterrelationships between adjacent transmissions 12, the drive shaftsof the transmissions will simultaneously rotate.

The transmission casing 32, in addition to including the primary or maincasing part 34, includes a secondary casing part 78 which iscomplementaryily shaped with respect to casing part 34 and mounts uponthe casing part 34 to define the complete transmission casing 32. Thecasing part 78 includes a flat parting surface 80, FIGS. 2 and 7, andincludes chambers corresponding to chambers 44 and 46 for receiving thegears 52 and 54, and the thrust bearing 56. Likewise, as laterdescribed, the casing part 78 includes recesses for accommodating thedrive shaft 48 and the output shaft 50. A plurality of holes 81 areformed in the casing part 78 intersecting the parting surface 80 andinclude enlarged countersunk portions 76 in alignment with the bosses 58whereby the bosses 58 will be located within the countersunk portions 76to facilitate alignment and assembly of the casing part 78 with thecasing part 34. Screws 82, FIGS. 2 and 7, extend through the holes 81and are received within the threaded holes 60 of the casing part 34 toassemble the casing parts 34 and 78 together. Usually, a thin gasket, orgasket material is located between the parting surfaces 36 and 80 whenassembling the casing parts to produce a fluid tight relationshipbetween the casing parts. Assembly of the casing parts 34 and 78 by thescrews 82 results in the assembled relationship shown in FIG. 2 and theinternal components of the transmissions 12 will be completely encased.

The drive shafts 48 of the transmissions 12 are rotated by a chainsprocket 84 mounted upon the input portion 66 of one of theinterconnected transmissions as will be appreciated from FIG. 2. Thechain sprocket 84 is connected to a transmission 86, FIG. 3, which isdriven by an electric motor 88 which is connected to controls, notshown, permitting intermittent operation of the motor 88. A chainsprocket 90 is mounted upon the output shaft of the transmission 86, andthe sprocket 90 is connected to the sprocket 84 by the chain 92.Accordingly, upon energizing of the electric motor 88, the transmission86 will slowly rotate the sprocket 90, and the sprocket 84 will berotated at an even slower speed and usually through only a 120°rotation. The transmission 86 is of the speed reduction type, and theintermittent operation of the motor 88, as closely timed by itscontrols, will accurately index the chain sprocket 84 as desired.

Rotation of the chain sprocket 84 will rotate the drive shaft 48 uponwhich the chain sprocket is mounted, and accordingly, all of thetransmissions 12 interconnected together as shown in FIGS. 1 and 2 willsimultaneously rotate producing a simultaneous indexing of the louvers10 to permit changing of the viewable face of the louvers, permittingthe louver face "behind" that previously visible to be observed.

As mentioned above, the secondary casing part 78 includes recesses forreceiving the drive shaft 48 and the output shaft 50. These recesses arelocated within the casing part 78 in opposed relationship to therecesses 38, 40 and 42 defined in the casing part 34. Thesecomplementary recesses formed in the secondary casing part 78 forreceiving the drive shaft 48 and the output shaft 50 will now bedescribed in conjunction with FIG. 7.

In FIG. 7, the relationship between the assembled casing part 34 andcasing part 78 as taken along Section 6--6 of FIG. 5 is illustrated uponthe casing parts 34 and 78 being assembled. The casing part 78 includesa recess 94, FIG. 7, for receiving the input portion 66 of the driveshaft 48, and the recess 94 is of a slightly larger dimension than thediameter of the recess 38 formed in the casing part 34. The diameter ofthe recess 38 is substantially equal to the diameter of the drive shaftportion 66, and the center of the recess 38 lies within the plane of theparting surface 36, such center being represented at 96 in FIGS. 6 and7, the center line of the shafts. The center of the recess 94 isrepresented at 98, and as will be appreciated from FIG. 7, the center ofthe recess 94 as shown at 98 lies "beyond" the plane of the partingsurface 80 of the casing part 78. The diameter of the recess 94 isapproximately 0.020 to 0.030 inches larger than the diameter of therecess 38, and by locating the center of the recess 94 beyond the planeof the parting surface 80, the recess 32 will include an apex at 100which is circumferentially equal distant from the intersections of therecess 94 to the parting surface 80 as represented at 101 in FIG. 7. Thelarger diameter of the recess 94 with respect to the diameter of thedrive shaft input portion 66 will produce clearances or radial spaces102 between the recess 94 and the shaft input portion 66 adjacent theparting surfaces. 36 and 80 as will be appreciated from FIG. 7.

With reference to FIG. 7, it will be appreciated that upon tightening ofthe screws 82 to bring the parting surfaces 36 and 80 into engagement,or substantial engagement as separated by a thin gasket or sealingmaterial, the location of the center 98 of the recess 94, and thediameter of the recess 94 is such that the apex 100 will engage thedrive shaft input portion 66 in a line contact and with such force as topermit rotation of the drive shaft within the recesses 38 and 94 in atypical sleeve bearing clearance relationship. The circumferentialextent of the recess 38 is 180°, while the circumferential extent of therecess 94 will be less than 180°, and the engagement of the apex 100 asdefined in the recess 94 is sufficient to maintain the drive shaft inputportion 66 in full engagement with the recess 38, and yet permitrotation of the drive shaft within the recesses 38 and 94. The forceexerted on the drive shaft portion 66 by the apex 100 will fullymaintain the drive shaft 48 within the recess 38 thereby accuratelylocating the drive shaft relative to the transmission casing parts 34and 78, and the practice of the invention permits the accommodating ofcasting tolerances existing during the casting of the casing parts 34and 78, and yet permits accurate positioning of the drive shaft withinthe transmission casing 32.

Preferably, the recesses defined in the secondary casing part 78 inopposed relationship to the primary casing part recesses 40 and 42 arealso constructed in accord with the concepts described above relative torecess 94. Accordingly, the drive shaft 48 and the output shaft 50 willbe accurately located within the transmission casing 32 by the linecontact produced by the casing part 78 with the associated shaft.

Of course, due to the direct engagement of the drive shaft 48 and outputshaft 50 with the shaft receiving recesses defined. in the casing parts34 and 78, the material of the casing parts, itself, becomes the bearingmaterial for the rotating shafts. Usually, the shafts 48 and 50 areformed of steel, while the casing parts are cast of an aluminum alloy.The elimination of separate bearings, bearing sleeves or moreconventional shaft supporting structure significantly reduces the costof transmissions 12 both from a fabricating and material standpoint, aswell as simplifying assembly of the transmissions and associatedcomponents. The elimination of separate bearing structure for the shafts48 and 50 is only possible due to the slow rate of indexing rotation ofthe shafts and the low lateral forces imposed upon the shafts in alouver sign environment. The shafts 48 and 50 will only index two orthree times a minute, and will index only 120° at a time. Due to therelative light weight of the louvers 10, and the support of the weightof the louvers on the thrust bearing 56, lateral forces imposed upon theshafts 48 and 50 are low, and the practice of the inventive conceptswithin a louver sign embodiment are possible due to the very low ratesof rotation or indexing of the transmission shafts through a partialrevolution. The practice of the invention in the environment of a louversign is particularly apropos in view of the need for large numbers oftransmissions 12 and the low cost fabrication and assembly oftransmissions 12 makes the use of louver sign transmissions constructedin accord with the invention feasible.

It is appreciated that various modifications to the inventive conceptsmay be apparent to those skilled in the art without departing from thespirit and scope of the invention.

I claim:
 1. A louver type sign transmission system for a louver signcomprising a plurality of parallel, rotatable, adjacent louvers eachhaving a plurality of indicia receiving surfaces and ends, comprising,in combination, an elongated support frame having first and secondsides, a plurality of transmissions mounted on said frame on a commonside thereof in side-by-side relationship, each of said transmissionsincluding a drive shaft drivingly connected to an output shaft, saiddrive shafts and said output shafts of said transmissions each having anaxis of rotation and the axes of rotation of said drive shafts of saidtransmissions being substantially coincident and parallel to the lengthof said frame, said axes of said output shafts being substantiallyperpendicular to said axes of said drive shafts and said output shaftsextending through said frame, each of said transmissions' drive shaftshaving an exteriorly accessible input end portion and an output endportion, a torque transmitting connector mounted upon each drive shaftend portion, said torque transmitting connectors mounted upon said driveshafts' input end portions drivingly interconnecting with said torquetransmitting connectors mounted upon said drive shafts' output endportion of an adjacent transmission whereby a plurality of adjacenttransmission drive shafts are operatively interconnected, a motordrivingly connected to one of said drive shaft end portions for rotatingsaid interconnected drive shafts, and a louver end support mounted uponeach transmission output shaft supporting a louver end, whereby saidtransmissions' drive shafts rotate the louver end associated therewithupon rotation of said drive shafts.
 2. In a louver type signtransmission as in claim 1, said torque transmitting connectorsincluding engaging drive surfaces radially disposed to the associateddrive shaft.
 3. In a louver type sign transmission as in claim 2,dimensional tolerances defined on said torque transmitting connectors'drive surfaces to accommodate limited radial misalignment of said driveshaft axes of adjacent transmissions.
 4. In a louver type signtransmission as in claim 1, said transmissions each including first andsecond casing parts defining a casing, removable fastenersinterconnecting said casing parts, a first gear within said casing fixedupon the associated transmission drive shaft, a second gear within saidcasing fixed upon the associated transmission output shaft and drivenlymeshing with said first gear, the material forming said first and secondcasing parts directly engaging said associated drive and output shaftsand defining the bearing for said shafts.
 5. In a louver type signtransmission system as in claim 1, said transmissions each includingfirst and second casing parts each having a parting surface and togetherdefining a casing, removable fasteners interconnecting said casing partswith said parting surfaces in opposed relationship and substantiallyengaging, a first semi-cylindrical recess defined in said first casingpart intersecting said parting surface thereof directly receiving theassociated drive shaft and having a diameter substantially equal to thereceived diameter of said drive shaft, a second substantiallysemi-cylindrical recess defined in said second casing part intersectingsaid parting surface thereof in opposed relation to said firstsemi-cylindrical recess when said casing parts are interconnected, saidsecond recess being of a diameter greater than the diameter of saidfirst recess, an apex defined on said second recess intermediate theintersection of said second part parting surface with said secondrecess, said apex engaging said drive shaft within said second recessupon said casing parts being fastened together at a limited locationwhereby said apex defines a bearing surface and maintains said driveshaft fully within said first recess.
 6. In a louver type signtransmission system as in claim 5, said apex defined on said secondrecess comprising the portion of said second recess equidistant from theintersections of said second part parting surface with said secondrecess.
 7. In a louver type sign transmission system as in claim 1, saidtransmissions each including first and second casing parts each having aparting surface and together defining a casing, removable fastenersinterconnecting said casing parts with said parting surfaces in opposedrelationship and substantially engaging, a first semi-cylindrical recessdefined in said first casing part within said associated parting surfacewherein the plane of said associated parting surface is diametricallyassociated to said first recess, said first recess having a diametersubstantially equal to the diameter of the drive shaft received therein,a substantially semi-cylindrical second recess defined in said secondcasing part within said associated parting surface thereof having acircumference and having a diameter greater than the diameter of saidfirst recess, the plane of said parting surface of said second partintersecting said second recess in a non-diametrical manner whereby thecircumference of said second recess is less than 180°, the location onsaid second recess circumference equidistant from the intersections ofsaid second casing parting surface with said second recess defining anapex within said second recess, said apex engaging said drive shaftwithin said second recess upon said casing parts being fastened togetherat a limited location whereby said apex defines a bearing surface andmaintains said drive shaft fully within said first recess.